Well i ll give u some tips 1-u should know the formulas for calculating different objects areas 2-find the length of their sides or diagonals(which are needed on the formula) 3-calculate the area
for example the triangle on the picture 1-s=leg1*leg2/2 2-the length of:leg1=10-3=7,,leg2=7-1=6 3-s=7*6/2=21